Custom Email Return Path

You can specify a custom return path for email sent by OpenAir.

To do so, go to Administration > Global Settings > Display > Email Settings and enter the custom return path in the Set up email return path box. Review the best practice guidelines before using this feature. See Custom Return Path Best Practice Guidelines.

By default, the Return-Path header (sometimes referred to as "envelope address") is set to [e-mail] by the OpenAir email relay server for all email messages originating from OpenAir. If you have a DMARC policy for your domain, this results in failing SPF alignment when the OpenAir application sends an email message with a user email address in the From header. See DMARC Alignment and OpenAir Email.

The Custom Email Return Path feature allows the Return-Path to be changed to a custom value when appropriate, depending on the scenario. If a custom return path is specified for your account and the custom return path domain matches the email header in the From domain, the OpenAir application sets the Return-Path header to this custom return path and tells the OpenAir email relay not to modify the Return-Path header.

The following table summarizes the three possible scenarios for OpenAir email when a custom return path is specified for the account. The example custom return path for all three scenarios is [e-mail].

Scenario	From header	Return-Path header	SPF Alignment	Notes
Email coming from user email address. From and custom return path email addresses have matching domains.	Account user email address. Example: [e-mail]	Set to custom return path by the OpenAir application. Example: [e-mail]	Pass	The email addresses in the From and Return-Path headers must have matching domains but may have different subdomains. If a forward email address is specified for undeliverable OpenAir email in Administration > Global Settings > Display > Email Settings, it has no impact in this scenario.
Email coming from [e-mail].	[e-mail]	Set by the OpenAir email relay server. [e-mail]	Pass	The custom Return-Path is not used.
Email coming from user email address. From domain matches neither the custom return path domain nor openair.com.	Account user email address Example: [e-mail]	Set by the OpenAir email relay server. [e-mail]	Fail	The email addresses in the From and Return-Path headers must have matching domains.

Custom Return Path Best Practice Guidelines

Review the following guidelines:

• You should specify an email address for undeliverable OpenAir email to be forwarded to. To do so, go to Administration > Global Settings > Display > Email Settings and enter the email address in the Forward undeliverable email to this email address box. See Email Settings.

• You should set a custom return path as a preventive measure if you send notification email from OpenAir with a custom From header such as the user email address. However, setting a custom return path is necessary only if email messages sent from OpenAir fail to be delivered – when Mimecast blocks email delivery with error 550 Envelope Blocked, for example. It offers little benefit over forwarding undeliverable email to a specific address otherwise.

  Note:

  Mimecast DMARC tool is the only known tool that checks SPF alignment. Generic mailing services, such as Microsoft Exchange, Gmail, or Yahoo, for example, omit SPF alignment checks by default. When email is sent to such mailboxes and a custom return path is specified for the account, all three scenarios pass.

• Bounce (undelivered) notification messages are sent to the address in the Return-Path header. If you specify a custom return path for your account:

  • In some scenarios, the custom return path bypasses the forward address for undeliverable OpenAir email as OpenAir no longer receives the bounce email notification.

  • You should set both the custom return path and the forward address for undeliverable OpenAir email (Forward undeliverable email to this email address) to the same email address.

  • The custom return path you enter must correspond to a valid email inbox on your email servers.

• Setting a custom return path does not provide a complete solution unless the From email domain is the same for all email sent with custom From header from your account. The feature has little to no use if you send OpenAir email from a wide range of email domains – Email messages would pass SPF alignment checks only for those custom From email addresses with a domain matching the Return-Path email domain; all other email with a custom From email address would fail SPF alignment.